JP2014067969A - Encapsulation material for solar cell module and solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an encapsulation material for a solar cell module capable of improving durability of the solar cell module and preventing a tab string from being visually recognized, and to provide a solar cell module having excellent durability and excellent appearance.SOLUTION: An encapsulation material 12 for a solar cell module contains an ethylene - vinyl acetate copolymer and an epoxy compound having an epoxy group and a vinyl group. A solar cell module 10 includes a solar cell 11 and a pair of the encapsulation material 12 for a solar cell module that holds the solar cell 11 in between.

Description

  The present invention relates to a solar cell sealing material for sealing solar cells and a solar cell module using the same.

In recent years, with the growing interest in environmental issues, the spread of solar power generation has been rapidly expanding. Usually, in solar power generation, a plurality of solar cells as power generation elements are sandwiched between a pair of sheet-like sealing materials in a state of being electrically connected, and these are further sandwiched between a transparent protective material and a back sheet. A solar cell module is used. As a sealing material for sealing a solar battery cell, a material mainly composed of an ethylene-vinyl acetate copolymer is widely used.
Since the solar cell module is installed outdoors, high durability is required. Therefore, Patent Document 1 proposes a method for improving the durability of a solar cell module by containing benzotriazole in a sealing material and suppressing deterioration of an ethylene-vinyl acetate copolymer as a main component. .

International Publication No. 2005/121227

However, even when the solar battery cell was sealed using the sealing material described in Patent Document 1, the durability of the solar battery module was insufficient. In particular, power generation performance tends to decrease under high-temperature and high-humidity environments and cold environments.
Further, when the solar cells are sealed using the sealing material described in Patent Document 1, the tab string connecting the solar cells becomes discolored and becomes visible, and the appearance as a solar cell module is obtained. There was a loss.
An object of this invention is to provide the sealing material for solar cell modules which can improve durability of a solar cell module and the visual recognition of a tab string is prevented. Another object of the present invention is to provide a solar cell module having high durability and excellent appearance.

The sealing material for solar cell modules of this invention contains the ethylene-vinyl acetate copolymer and the epoxy compound which has an epoxy group and a vinyl group.
In the sealing material for solar cell modules of this invention, it is preferable that content of the said epoxy compound is 0.05-5.0 mass parts with respect to 100 mass parts of ethylene-vinyl acetate copolymers.
The solar cell module of the present invention includes a solar cell and a pair of solar cell encapsulants sandwiching the solar cell, and the solar cell module encapsulant is the solar cell module encapsulant. is there.

The sealing material for solar cell modules of this invention is excellent in durability of a solar cell module, and can prevent visual recognition of a tab string.
The solar cell module of the present invention has high durability and excellent appearance.

It is sectional drawing which shows one embodiment of the solar cell module of this invention.

<Sealant for solar cell module>
The solar cell module sealing material of the present invention (hereinafter abbreviated as “sealing material”) is a sheet containing an ethylene-vinyl acetate copolymer (hereinafter referred to as “EVA”) and an epoxy compound. .

(EVA)
EVA has a vinyl acetate unit ratio of preferably 10 to 40% by mass, and more preferably 15 to 35% by mass. If the proportion of vinyl acetate units in EVA is not less than the lower limit, the transparency and adhesiveness of the sealing material can be increased when the solar cell module is formed. If the ratio is not more than the upper limit, the durability of the solar cell module can be improved. The sex can be made higher.
The mass average molecular weight of EVA is preferably 10,000 to 300,000, and more preferably 30,000 to 100,000. If the EVA mass average molecular weight is equal to or higher than the lower limit, the mechanical properties of the encapsulant when the solar cell module is made can be improved, and if the EVA is equal to or lower than the upper limit, the processability of the encapsulant is improved. it can.

(Epoxy compound)
The epoxy compound in the present invention is a compound having an epoxy group and a vinyl group.
In this epoxy compound, the vinyl group reacts with the crosslinking agent and the epoxy compound is incorporated into the crosslinking system, so that it is difficult to bleed out from the sealing material even with a low molecular weight of 200 or less.
The number of epoxy groups and the number of vinyl groups are not particularly limited. For example, the number of epoxy groups may be 2 or less, and the number of vinyl groups may be 2 or less.

  Specific examples of the epoxy compound include EX-111 (Nagase ChemteX Corporation), Bremer GH (Nippon Oil Corporation), and the like.

  The content of the epoxy compound is preferably 0.05 to 5.0 parts by mass, and more preferably 0.2 to 3.0 parts by mass. If the content of the epoxy compound is equal to or higher than the lower limit value, the durability of the solar cell module is further increased. If the content is equal to or lower than the upper limit value, the mechanical properties of the sealing material when the solar cell module is obtained are improved. it can.

(Triazole compound)
The encapsulant may contain a triazole compound in order to further improve the durability of the solar cell module.
The triazole compound is a derivative in which a hydrogen atom of a nitrogen-containing heterocyclic ring of triazole or triazole is substituted with a substituent. However, the triazole compound does not include benzotriazole.
Examples of the substituent include alkyl groups such as a methyl group, an ethyl group, and a propyl group.
The alkyl group may be further substituted with an amino group, a halogen atom or the like.
In addition, as a triazole compound, trade name irgamet 30 (N, N-bis (2-ethylhexyl) -1,2,4-triazol-1-ylmethanamine) is a trade name from ADEKA Co., Ltd. from BASF Japan. Adekastab CDA-1 (3- (N-salicyloyl) amino-1,2,4-triazole) is commercially available.
The content of the triazole compound is preferably 0.001 to 5 parts by mass, and more preferably 0.2 to 1.0 part by mass. If the content of the triazole compound is equal to or higher than the lower limit, the durability of the solar cell module is further increased. If the content of the triazole compound is equal to or lower than the upper limit, the mechanical properties of the sealing material when the solar cell module is obtained are improved. it can.

(Additive)
The sealing material may contain additives such as an ultraviolet absorber, a light stabilizer, an antioxidant, a silane coupling agent, a crosslinking agent, and a crosslinking aid.

Examples of the ultraviolet absorber include benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and salicylic acid ester-based ultraviolet absorbers.
Examples of the light stabilizer include hindered amine light stabilizers.
Examples of the antioxidant include hindered phenol antioxidants and phosphite antioxidants.

A silane coupling agent is a component which improves adhesiveness with the photovoltaic cell mentioned later, a transparent protective material, a back sheet | seat, etc. As the silane coupling agent, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, N-2- (aminoethyl) -3 -Aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane and the like.
0-10 mass parts is preferable with respect to 100 mass parts of resin, and, as for the compounding quantity of a silane coupling agent, 0-5 mass parts is more preferable.

The crosslinking agent is a component that crosslinks EVA. Examples of the crosslinking agent include known organic peroxides (peroxyketals, dialkyl peroxides, peroxyesters, etc.), photosensitizers and the like.
0-5 mass parts is preferable with respect to 100 mass parts of EVA, and, as for the compounding quantity of a crosslinking agent, 0-2 mass parts is more preferable.

The crosslinking aid is a compound having one or more (preferably two or more) polymerizable unsaturated groups (vinyl group, allyl group, (meth) acryloxy group, etc.). Examples of the compound include triallyl isocyanurate, triallyl cyanurate, and trimethylolpropane trimethacrylate.
0-20 mass parts is preferable with respect to 100 mass parts of EVA, and, as for the compounding quantity of a crosslinking adjuvant, 0-10 mass parts is more preferable.

  In addition to the above additives, the sealing material may contain pigments, dyes, fillers, and the like.

(Thickness)
The thickness of the sheet-shaped sealing material is appropriately selected within the range of 0.05 to 1 mm according to the solar cell module to be produced. If the thickness of the sealing material is 0.05 mm or more, the solar battery cell can be sufficiently sealed, and if it is 1 mm or less, the solar battery cell can be thinned.

(Method for producing sealing material)
As a manufacturing method of a sealing material, the method of mixing EVA, an epoxy compound, and an additive as needed, preparing a mixture, shape | molding this mixture, and making it into a sheet | seat is mentioned.
Examples of the sheet forming method include an extrusion molding method using a T die, a press molding method, and the like. Moreover, it can also make into a sheet | seat by apply | coating the solution of a sealing material to a release sheet, and drying.

<Solar cell module>
Next, an embodiment of a solar cell module using the sealing material will be described.
In FIG. 1, sectional drawing of the solar cell module of this embodiment example is shown. The solar cell module 10 of the present embodiment includes a plurality of solar cells 11, 11..., A pair of sealing materials 12, 12, a transparent protective material 13, and a back sheet 14. The solar battery cell 11 is sandwiched and fixed between a pair of solar battery sealing materials 12 and 12. Further, the sealing materials 12 and 12 are disposed between the transparent protective material 13 and the back sheet 14.

(Solar cell)
Examples of the solar battery cell 11 include a pn junction solar battery element having a structure in which a p-type semiconductor and an n-type semiconductor are joined. Examples of the pn junction type solar cell element include silicon (single crystal silicon, polycrystalline silicon, amorphous silicon, etc.), compound (GaAs, CIS, CdTe-CdS) and the like.
In the present embodiment example, the plurality of solar cells 11 are electrically connected in series via a tab string 15 having a conductive wire and a solder joint.

(Transparent protective material)
Examples of the transparent protective material 13 include a glass plate and a resin plate. As a glass plate, the template glass which gave the surface unevenness | corrugation from the point of light transmittance is preferable. As the material of the template glass, white plate glass (high transmission glass) with less iron content is preferable.

(Back sheet)
Examples of the material of the back sheet 14 include polyvinyl fluoride, polyester (polyethylene terephthalate, etc.), polyolefin (polyethylene, etc.), glass, metal (aluminum, etc.) and the like. The backsheet 24 may be a single layer or a multilayer.

(Method for manufacturing solar cell module)
As a manufacturing method of the solar cell module 10, a plurality of solar cells 11, 11... Electrically connected using a tab string 15 are sandwiched between a pair of sealing materials 12, 12. 12 is sandwiched between the transparent protective material 13 and the back sheet 14, and then heated to bond the sealing materials 12 and 12, the sealing material 12 and the transparent protective material 13, and the sealing material 12 and the back sheet 14 together. A method is mentioned.
When the sealing material 12 contains a crosslinking agent, it is preferable to heat it above the decomposition temperature of the crosslinking agent. When heated to a temperature equal to or higher than the decomposition temperature of the crosslinking agent, EVA contained in the sealing material 12 can be crosslinked, and the durability of the sealing material 11 can be further improved.

(Function and effect)
In the present invention, the epoxy compound contained in the sealing material 12 can react with acetic acid generated by EVA deterioration to inactivate acetic acid. Therefore, the corrosion of the tab string by acetic acid can be prevented, and the appearance as the solar cell module 10 can be improved. Prevention of tab string corrosion also contributes to improved power generation.
Moreover, since the epoxy compound contained in the sealing material reacts with the EVA and the crosslinking agent by the vinyl group and is immobilized, it is difficult to bleed out. Therefore, acetic acid can be inactivated continuously and the durability of the solar cell module 10 can be improved. In particular, the durability under high-temperature and high-humidity environments and cold environments is increased, and power generation performance can be maintained.
And since an epoxy compound is a non-particulate organic substance, the transparency fall of the sealing material 12 can be suppressed. Moreover, since the adhesiveness with respect to the transparent protective material 13 of the sealing material 12 by the bleeding out of an epoxy compound is prevented, the fall of the light transmittance by peeling with the sealing material 12 and the transparent protective material 13 is prevented. Yes. Therefore, since most of the sunlight incident on the sealing material 12 can be incident on the solar battery cell 11, sufficiently high power generation performance can be obtained.

Example 1
100 parts by mass of ethylene-vinyl acetate copolymer (SEETEC VE700 manufactured by Hunan Petrochemical Co., Ltd., proportion of vinyl acetate units: 28% by mass), 0.5 part by mass of UV absorber (TINUVIN P manufactured by BASF Japan Ltd.), light stability 0.5 parts by weight of the agent (TINSFIN114 manufactured by BASF Japan), 0.5 parts by weight of the silane coupling agent (KBM-503 manufactured by Shin-Etsu Silicone Co., Ltd.), 0.5 parts by weight of the crosslinking agent (Kayahexa AD manufactured by Kayaku Akzo) Cross-linking aid (Nippon Kasei Co., Ltd.) 0.5 parts by mass, triazole compound (BASF Japan irgamet 30) 0.5 parts by mass, and epoxy- and vinyl group-containing compound A (Nagase ChemteX EX- 111, molecular weight 114) and 0.5 parts by mass were mixed to obtain a composition for a sealing material. Subsequently, the obtained composition for sealing materials was press-molded to obtain a sheet-shaped sealing material having a thickness of 500 μm.
Then, between the two sealing materials obtained as described above, one polycrystalline silicon solar cell with the tab string fixed is sandwiched between them, a glass plate, a back sheet made of polyvinyl fluoride and polyester, To obtain a laminate. The laminated body was put in a resin bag, the inside of the bag was evacuated and heated to 150 ° C., and then the tab string taken out of the module was connected to obtain an experimental single cell solar cell module.

(Example 2)
A solar cell module was obtained in the same manner as in Example 1 except that the amount of the compound A having an epoxy group and a vinyl group was changed to 1.0 part by mass.

(Example 3)
A solar cell module was obtained in the same manner as in Example 1 except that the amount of the compound A having an epoxy group and a vinyl group was changed to 3.0 parts by mass.

(Comparative Example 1)
Except having changed the compound A which has an epoxy group and a vinyl group into the compound B which has an epoxy group and does not have a vinyl group (Nagase ChemteX Corporation EX-216L, molecular weight 256), it carries out similarly to Example 1. A solar cell module was obtained.

(Comparative Example 2)
A solar cell module was obtained in the same manner as in Example 2 except that the compound A having an epoxy group and a vinyl group was changed to the compound B having an epoxy group and not having a vinyl group.

(Comparative Example 3)
A solar cell module was obtained in the same manner as in Example 3 except that the compound A having an epoxy group and a vinyl group was changed to the compound B having an epoxy group and not having a vinyl group.

(Comparative Example 4)
A solar cell module was obtained in the same manner as in Example 1 except that the compound A having an epoxy group and a vinyl group was changed to magnesium oxide.

(Comparative Example 5)
A solar cell module was obtained in the same manner as in Example 1 except that the compound A having an epoxy group and a vinyl group was not blended.

<Evaluation>
Each solar cell module obtained was measured or evaluated for power generation performance, power generation maintenance ratio after high-temperature and high-humidity test or after condensation freeze test, tab string appearance, transparency, and adhesive strength of the sealing material to glass. The results are shown in Table 1.

[Power generation performance and power generation maintenance rate (P _max maintenance rate)]
Using the solar simulator (Nisshinbo Mechatronics PVS1114iD), the IV characteristic of the obtained solar cell module was measured, and the initial power generation amount (maximum power P _max ) was obtained. Next, the solar cell module was subjected to a high temperature and high humidity test in which the solar cell module was left in an environment of 85 ° C. and 85% relative humidity for 5000 hours, and then the amount of power generation was measured. And the power generation maintenance rate was calculated | required from the type | formula of [(the power generation amount after a high temperature, high humidity test / initial power generation amount) x100].
In addition, after the initial power generation performance measurement, the amount of power generation was measured after 100 cycles of a condensation freezing test in which an environment of −40 ° C., a temperature of 85 ° C., and a relative humidity of 85% was repeated. Then, the power generation maintenance rate (P _max maintenance rate) was obtained from the formula [(power generation amount after condensation freezing test / initial power generation amount) × 100].

[Tab string appearance]
The obtained solar cell module was allowed to stand for 5000 hours in a moist heat environment at a temperature of 85 ° C. and a relative humidity of 85%, and then the appearance of the tab string was visually observed and evaluated according to the following criteria.
○: Rust, discoloration, and cloudiness are not observed.
Δ: Slightly rusted, discolored, or cloudy, but can be used.
X: Rust, discoloration, or cloudiness is seen and cannot be used.

[transparency]
Based on JIS K7136, the HAZE value was measured with a haze meter NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.) and evaluated according to the following criteria.
○: HAZE ≦ 2
×: HAZE> 2

[Adhesive strength of sealing material to glass]
Using a tensile tester (AG-5000A, manufactured by Shimadzu Corporation), the adhesive strength between the sealing material and the glass plate in the obtained solar cell module was 180 ° peel test at a tensile rate of 200 mm / min in an environment of 23 ° C. The peel strength was measured. The peel strength was measured after the high temperature and high humidity test. Based on the measured peel strength, the following criteria were used for evaluation.
Initial ○: 20 N / 10 mm or more.
X: Less than 20N / 10mm.
High temperature and high humidity test ○: 15 N / 10 mm or more.
X: Less than 15N / 10mm.

In the solar cell modules of Examples 1 to 3 in which the compound having an epoxy group and a vinyl group was contained in the encapsulant, the power generation performance after the high-temperature and high-humidity test and after the condensation freezing test was high, and the durability was excellent. Moreover, the adhesive force fall with respect to the glass of the sealing material after a high temperature, high humidity test was prevented. Moreover, since the tab string was not visually recognized and the transparency was high, it had a good appearance.
In the solar cell modules of Comparative Examples 1 to 3 in which a compound having an epoxy group and no vinyl group is contained in the encapsulant, the power generation performance after the high temperature and high humidity test and after the condensation freezing test is low, and durability Was insufficient. Moreover, the adhesive force with respect to the glass of the sealing material after a high temperature, high humidity test fell.
In the solar cell module of Comparative Example 4 in which magnesium oxide was used instead of the compound having an epoxy group and a vinyl group, the apparent haze was increased, resulting in poor appearance.
In the solar cell module of Comparative Example 5 in which the acid acceptor was not included in the sealing material, the tab string became visible and a poor appearance occurred.

DESCRIPTION OF SYMBOLS 10 Solar cell module 11 Solar cell 12 Sealing material 13 Transparent protective material 14 Back sheet 15 Tab string

Claims (3)

  The sealing material for solar cell modules containing an ethylene-vinyl acetate copolymer and the epoxy compound which has an epoxy group and a vinyl group.   The encapsulant for a solar cell module according to claim 1, wherein the content of the epoxy compound is 0.05 to 5.0 parts by mass with respect to 100 parts by mass of the ethylene-vinyl acetate copolymer.   A solar cell module provided with a photovoltaic cell and a pair of sealing material for solar cells of Claim 1 or 2 which clamped this photovoltaic cell.

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